i dont think its the smg but more on the plyer than the gun.. u might need to be more skilledful with them (except the 74u need no skill at all) SMG'S arnt made to go head on with an assault rifle or with anything else...smg's are more on flanking and CQ.. ur not gonna snipe some1 with a mac11, but get closer to that person and flank them. u also gotta know the maps..
i use alot of single fire weapons and pistols then fullauto but i dont go head to head ill get raped, but like i said flanking and speed is the smg's best friend.. i can still dominate with the silance uzi with scout pro and my asp..
btw i also hate the dumbass snipers out there mostly on SnD.. running with the sinper come on man pull out ur pistols.. or quickscoping from a long range, just hardscope .. i know im not the greatest sniper but im smarter than the some of the dumbass snipers out there, dont get me wrong if ur super good at snipping then ill give u props, but still ply smart.. mostly on SnD
sorry if i got a liitle off topic, hope this helps or not ...